Just today I noticed that in 10.5 iChat started to organize the chat transcripts held in ~/Documents/iChats/. Here is a script you can use to organize all of your pre 10.5 chats in the new iChat v4 places:

#!/bin/bash                                            
DIR="${HOME}/Documents/iChats"

for I in $DIR/*.ichat
do
    if [ ! -e "$I" ]
    then
        break
    fi

    D=$I
    D=${D##*on }
    D=${D%% at*}

    if [ ! -d "$DIR/$D" ]
    then
        mkdir "$DIR/$D"
    fi
    mv "$I" "$DIR/$D/"

    echo ${I#$DIR/}
done

echo "FINISHED"

And if you’re always changing IPs this can be handy:

find ./ -name "AOL System Msg" -print0 | xargs -0 rm